The present invention relates to a system and method for monitoring a freight container and, in particular, for identifying the contents of the freight container, for detecting whether the boundary of the container has changed in any respect, and for detecting whether the contents have shifted or been moved during transport.
Containerized shipping is the most common method of freight shipment in today's economy. About 90% of the $12.5 trillions of merchandise traded worldwide was handled by containerized shipping involving about 200 million freight containers in the intermodal transportation between the major seaports around the world.
While containerized shipping brings great advantage to efficient and low cost freight shipment, it also opens the door to a variety of freight container related crime. Further, unsecured freight containers represent a global security threat. Terrorist attacks involving freight container transportation systems could cause an extended shutdown in freight deliveries, physical destruction, loss of life, and lost production in contaminated areas. Still further, freight containers are being used as a way to smuggle people undetected into countries, which will bring social instability to our society.
The integrity of freight shipments have become an important issue for governments, security agencies, ports, insurance companies, shippers, transportation companies, and the manufacturers who depend on the containerized supply chain to receive raw materials and deliver finished goods.
A wide variety of systems have been developed for detecting, analyzing and monitoring the contents of freight containers and the like. One such system is shown in published U.S. patent application No. 2003/01895190 to Anderton et al. The Anderton et al. system images the contents of containers. The system includes an imager arranged to receive millimeter wave radiation from a reception volume through a reception antenna, wherein the container is moving relative to the receive antenna. The reception volume is positioned such that the relative movement causes the reception volume to move through the container. Data from the antenna is recorded as the reception volume moves through the container. An image of the contents of the container is built up from the recorded data. The imager may be mounted in a portal for allowing relative positioning of the container and allowing relative speed to be controlled.
U.S. Pat. No. 5,910,973 to Grodzins relates to an inspection system for detecting the presence of a concealed item within an enclosure, such as a freight container. A beam of penetrating radiation is incident on the enclosure and detected by a detector disposed on the side of the enclosure opposite to the incident beam. By scanning the relative orientation of the enclosure with respect to the beam, the penetrating radiation transmitted through the enclosure is mapped, compared with known properties of the enclosure, and the presence of material concealed within the enclosure is determined.
U.S. Pat. No. 6,552,346 to Verbinski et al. relates to a system and method of density detection in a target object, such as a tanker truck. The system and method involve irradiating the target object, detecting a first and second discrete number of photons penetrating the target object through respective first and second prescribed volumes and entering respective first and second radiation detectors. First and second numbers of photons are detected by the first and second radiation detectors and are counted. A display output signal is generated in response to the first and second numbers. A graphical representation of the densities within the first and second volumes of the target object is displayed.
U.S. Pat. No. 5,524,133 to Neale et al. relates to a system for identifying materials using X-rays. The system detects the mean atomic number of a mass of material, for example freight in a vehicle. The method employed by the system involves subjecting the mass to X-rays and determining a first mean number passing there through. Thereafter, the mass is subject to higher energy X-rays and a second mean number is determined. The mean atomic number of the mass is determined from look-up tables against the ratio of the first mean number to the second mean number. The mass may be scanned by two linear accelerators arranged perpendicular to each other. Detector arrays are disposed respectively opposite the accelerators so that a three dimensional image can be built up of the mass.
U.S. Pat. No. 6,344,818 to Markov relates to a device to detect the presence of a target material. The device has a source module and a detector module. The source module includes a generator for producing a source signal corresponding to a characteristic frequency of the target material. The detection nodule detects a location of the target material wherein the detection module detects an interference signal generated between the source signal and a signal generated by the target material caused by the exposure to the source signal.
U.S. Pat. No. 6,647,091 to Fenkart et al. relates to an X-ray based inspection apparatus. Features of the apparatus include radiation locking with active curtains, continuous scanning utilizing an X-ray line scanner subsystem, and a CT scanner subsystem. The apparatus is used to inspect containers.
U.S. Pat. No. 6,047,588 to Danilychev relates to an air cargo container that a system for analyzing gases drawn from the container to detect the presence of contraband within any received cargo. Sensors on a housing of the container are used to confirm that an achieved interior pressure is substantially maintained over time.
U.S. Pat. No. 6,542,580 to Carver et al. relates to an X-ray imaging system for inspecting vehicles and containers. The inspection system includes a substantially rectangular frame having an X-ray imaging system disposed thereon. The frame is detachably connected to a conveyor mechanism which conveys a vehicle or container to be inspected through the imaging system.
U.S. Patent Application Publication Nos. 2003/0160701 and 2003/0164763, both to Nakamura et al., relate to a multifunction wireless self-organized sensor network system for the freight container security. The system uses proximity sensors to form a topological and geometrical network configuration to monitor a freight container boundary and the contents inside the freight container. U.S. Pat. No. 5,615,247 and Japanese patent publication No. 09-274077 also relate to security monitoring systems for freight container.
Despite the existence of these systems, there remains a need for an improved system, which can identify the contents of the freight container as well as ensure the security of the boundary and the contents of the freight container.